Filter Cleaning With An Engine Idle Bump

ABSTRACT

Disclosed is a method of filter regeneration employing an automatic increase in the minimum speed of an engine when a vehicle is in a parked state. The filter regeneration until the operator cancels it or filter regeneration is determined to be complete.

FIELD OF THE INVENTION

This invention relates to emission control systems in motor vehicles powered by internal combustion engines and, more particularly, vehicles powered by diesel engines with exhaust gas treatment devices requiring regeneration.

BACKGROUND OF THE INVENTION

Diesel particulate filters (DPFs) form a known part of certain diesel engine exhaust gas systems trapping significant amounts of pollutants such as hydrocarbons, carbon monoxide and ash as the exhaust gas travels through them, i.e., the DPFs. Engine efficiency may decrease as the amount of pollutants the DPF has entrapped increases. It is, therefore, incumbent on the operator/owner of the vehicle to at least periodically regenerate, i.e., clean the DPF.

DPFs may be regenerated by raising the temperature of their internal temperatures to a temperature suitable for flashing and flushing the pollutants, i.e., cleaning the DPFs. Such a rise in temperature may be accomplished by increasing the temperature of the exhaust gases passing through the DPFs. In cold conditions, a rise in exhaust gas temperatures may be accomplished by an increased load on the engine. Increasing the volume of exhaust gas throughput may enhance the flushing of such pollutants. There are a variety of methods used to increase the temperature of gases flowing through the DPFs, many of which are complex and/or cumbersome.

SUMMARY OF THE INVENTION

Disclosed is a method of increasing exhaust gas temperatures to threshold temperatures for DPF regeneration via automatic increase in engine idle speed to a predetermined engine speed at high soot levels until regeneration is complete, i.e., the detected soot level is low or 0. This may be especially helpful in colder climates (temperatures lower than 0° C.) where an operator is likely to want to leave a vehicle running for an extended period of time, i.e., for example, over a weekend.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a vehicle which may make use of the invention;

FIG. 2 is a schematic of an engine and control system;

FIG. 3 is an alternative view of the engine and control system with controller 100; and

FIG. 4 is a flowchart illustrating the workings of an embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a side view of a work vehicle, i.e., a loader 10 having an operator cab 20; wheels 30 for powered movement along the ground; and an engine 40. Such a work vehicle, as well as others, may be suitable for use of the invention.

FIG. 2 is a schematic of parts of the vehicle involved in an exemplary embodiment of the invention. Illustrated is a vehicle controller unit (“VCU”) 15 which controls various functions of the vehicle 10; an engine 40; an engine speed sensor 40 a; an exhaust 40 b providing a route for engine exhaust gases; a throttle 41 capable of being engaged and not engaged; a throttle position sensor 41 a capable of detecting whether the throttle 41 is engaged or not engaged; an engine oil pressure sensor 42 a; an engine coolant temperature sensor 43; an engine coolant level sensor 44; an engine controller unit (“ECU”) 45 capable of controlling the functions of the engine 40; a transmission 50 capable of being in a forward, a reverse, or a neutral gear; a transmission gear sensor 50 a; a park brake 55 capable of being engaged and disengaged; a park brake sensor 55 a capable of detecting if the park brake 55 is engaged or disengaged; an ignition 60 having an on position and an off position through which the vehicle may be powered by an electrical power source 70 which may be a battery, an alternator or some other device when the ignition is in a first position and the vehicle 10 is shutdown when the ignition 60 is in a second position; a diesel particulate filter (“DPF”) 80; an exhaust gas temperature sensor 81; a fuel dosing injector 82; a diesel oxidation catalyst (“DOC”) 83; and a timer 90 by which the ECU 45 and the VCU 15 measure time passed.

In this exemplary embodiment, during a regeneration of the DPF 80, the exhaust gas exiting the engine 40 is dosed with fuel via the fuel dosing injector 82 as it travels to the DOC 83 where its temperature may be raised, via additional burning, to approximately 575° C. prior to entering the DPF 80. This high temperature may be required to effect regeneration of the DPF 80. In order to attain this end temperature it may be necessary to have the exhaust gas at a temperature of at least 275° C. as it exits the engine 40. Increases in engine speed may have the effect of raising exhaust gas temperatures. In cold climates, the inventor has determined that, for this exemplary embodiment, a minimum engine speed of 1200 rpm may constitute an engine load sufficient to raise the exhaust gas temperature to the minimum of 275° C. as the exhaust gas exits the engine 40.

FIG. 3 illustrates how the sensors, the timer 95 and a warning device 96 may communicate with the controller unit combination 100. In this exemplary embodiment the warning device 96 may be a monitor, audible sound generator or some other device which may include a switch and may, among other things, indicate: the vehicle 10 is ready for idle bump regeneration of the DPF 80; the vehicle 10 will/has started idle bump regeneration of the DPF 80; idle bump regeneration of the DPF 80 has been completed; or idle bump regeneration of the DPF 80 has been canceled by the operator.

The vehicle 10 is considered in a parked state, i.e., a state suitable for idle bump, when the following conditions exist: (1) the ignition 60 is on; (2) the engine 40 is running; (3) the transmission 50 is in a neutral gear; (4) the park brake 55 is engaged; (5) the engine speed is at standby idle, i.e., the throttle 42 is not engaged; (6) the DPF soot level is high; and (7) alternate regeneration methods are not active. The ECU 45 may determine soot level by: monitoring exhaust gas temperatures over time and using a lookup table to calculate the difference between soot accumulated over time and soot burned or oxidized over time; or simply as a function of the accumulated time over which the engine has been running based on experiential data. Times over which soot is accumulated may be times over which exhaust gas temperatures are lower than a threshold temperature as it exits the engine. Times over which soot is burned may be times over which exhaust gas temperatures are at least equal to the threshold temperature as it exits the engine. Whatever the method used to make the determination, it is the ECU 45 that determines the soot level in this exemplary embodiment. The VCU 15 may direct the regeneration of the DPF 80 via idle bump, i.e., an increase in engine speed, when the vehicle 10 is in the parked state. Unless the operator cancels regeneration, idle bump regeneration may continue until regeneration is complete even if the operator begins work operations, taking the vehicle out of the parked state. An exemplary idle bump regeneration process will now be described below.

The exemplary idle bump regeneration process begins when the vehicle is in a parked state and the ECU 45, upon determining that the DPF soot level is high, signals the VCU 15 to begin the idle bump process for regenerating the DPF 80. The VCU 15 then takes control of the engine speed command and requests an engine speed increase to a first predetermined engine speed which, in this exemplary embodiment, may be 1250 rpm. Once the first predetermined engine speed is achieved, the VCU 15 may release control of the engine and allow the ECU 45 to set a second predetermined engine speed, which, in this exemplary embodiment, may be 1200 rpm, below which the engine will not be allowed to go, i.e., to latch the engine speed at the second predetermined engine speed. The engine speed may be latched at 1200 rpm until the regeneration of the DPF 80 is complete or the operator cancels the process via a switch which may be located on the warning device 96 or by shutting down the vehicle 10.

FIG. 4 illustrates a flowchart that may represent the manner in which this exemplary embodiment works. As illustrated in FIG. 4, the entire process may begin at step 100 with the ignition 11 and the engine 40 on. Once the ECU 45 determines that the soot level is at a predetermined level, i.e., that it is high at step 110, and the VCU 15 determines that the vehicle is in a parked state, i.e., the park brake sensor 55 a indicates that the park brake 55 is engaged at step 120; the transmission sensor 50 a indicates that the transmission 50 is in a neutral gear at step 130; and the engine speed is at standby idle, i.e., the throttle position sensor 41 a indicates the throttle 40 is not engaged at step 140, the VCU 15 takes control of engine speed commands at step 150 and, if idle bump is not canceled by the operator at step 151, increases engine speed, at step 152, to the first predetermined engine speed which, in this exemplary embodiment, may be a speed equal to or greater than 1250 rpm. Once the first predetermined engine speed is achieved at step 152, at step 160, the warning device 96 informs the operator that engine idle speed has been increased, the VCU 15 releases control of engine speed commands and signals the ECU 45 to latch the engine speed to a second predetermined engine speed whereupon, at step 165, the ECU 45 latches the engine speed at the second predetermined engine speed which, in this exemplary embodiment may be 1200 rpm. If the idle bump is not canceled by the operator, at step 170, the ECU 45 continues with the latch at step 180 until the ECU 45 determines that regeneration of the DPF 80 is complete, at which time, the ECU 45 cancels the idle bump regeneration, i.e., unlatches the second predetermined engine speed and allows the engine speed to return to the standby idle setting. The operator may cancel idle bump regeneration at any time, i.e., at step 151 or 170, by shutting down the vehicle 10 or manipulation of a mechanical or electronic switch which may be located on the warning device 96. Unless the operator cancels idle bump regeneration, it will continue until regeneration is complete.

Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims. 

1. A method of filter regeneration for a work vehicle having an engine, a park brake capable of being engaged or disengaged, a throttle capable of being engaged or not engaged, the method comprising: a. monitoring engine speed with an engine speed detector; b. monitoring a status of the park brake with a park brake sensor; c. monitoring a status of the throttle with a throttle sensor; and d. automatically latching the engine speed to a predetermined engine speed sufficient for filter regeneration when the engine is running, the park brake is engaged, and the throttle is not engaged.
 2. The method of claim 1, further comprising continuing the latching of the engine speed to the predetermined engine speed until the filter regeneration is complete.
 3. The method of claim 1, further comprising continuing the latching of the engine speed to the predetermined engine speed until an operator cancels the filter regeneration.
 4. A method of filter regeneration for a work vehicle having an ignition capable of being on and off, a filter capable of accumulating soot, an engine capable of being started and not started, a temperature sensor for detecting a temperature of the exhaust gas exiting the engine, a park brake capable of being engaged and disengaged, a throttle capable of being engaged and not engaged, the method comprising: a. monitoring a status of the park brake with a park brake sensor; b. monitoring a status of the throttle with a throttle sensor; c. monitoring a temperature of the exhaust gas exiting the engine with a temperature sensor; d. monitoring an engine speed with an engine speed sensor, the engine speed being at standby idle when the status of the throttle is not engaged; e. calculating a soot level for the filter; and f. automatically latching the engine speed to a predetermined engine speed for raising a temperature of the exhaust gas exiting the engine to at least a predetermined temperature sufficient for filter regeneration only if: (1) the engine is started, (2) the park brake sensor detects a status of engaged; (3) the engine is at idle standby; (4) the temperature sensor detects an exhaust gas temperature below a predetermined threshold temperature; and the calculated soot level is high.
 5. The method of claim 4, further comprising continuing the latching of the engine speed to the predetermined engine speed until the filter regeneration is complete.
 6. The method of claim 4, further comprising continuing the latching of the engine speed to the predetermined engine speed until an operator cancels the filter regeneration.
 7. A system for exhaust filter regeneration in a work vehicle having an exhaust filter capable of accumulating soot at levels varying from negligible to high, comprising: an engine capable of being started and not started; an engine speed sensor for detecting a speed of the engine; a throttle capable of being engaged and not engaged; a throttle sensor for detecting whether the throttle is engaged or not engaged, the engine being at standby idle when the throttle is not engaged and filter regeneration is not enabled; a temperature sensor for detecting the temperature of the exhaust gas as it exits the engine; a transmission having a neutral setting, and a non-neutral setting; a transmission sensor for detecting the setting of the transmission; a park brake capable of being engaged and disengaged; a park brake sensor capable of detecting whether the park brake is engaged or disengaged; an ignition capable of being on and off; at least one controller for controlling functions of the engine, for detecting a filter soot level and for controlling functions of the vehicle; and a timer for timing a duration of an event, the at least one controller initiating an increase in engine speed to a first predetermined level only when: (1) the ignition is on, (2) the engine is running, (3) the engine is at standby idle, (4) the park brake is engaged, (5) the transmission sensor detects a neutral setting, (6) the temperature sensor detects an exhaust gas temperature lower than a predetermined temperature required for filter regeneration, and the detected filter soot level is high.
 8. The system of claim 7, wherein the controller latches the engine speed to a second predetermined engine speed for filter regeneration upon the engine achieving the first predetermined engine speed.
 9. The system of claim 8, wherein the controller continues to latch the engine speed at the second predetermined engine speed until the controller determines filter regeneration is complete.
 10. The system of claim 8, wherein the at least one controller continues to latch the engine speed at the second predetermined engine speed until the operator cancels the filter regeneration by at least one of turning the ignition off or instructing the at least one controller to cancel the filter regeneration.
 11. The system of claim 8, wherein the at least one controller comprises an engine control unit for controlling functions of the engine and a vehicle controller unit for controlling functions of the vehicle and temporarily controlling engine speed when initiating filter regeneration. 